Vanadium cell soc balanced system

ABSTRACT

The application relates to a vanadium battery SOC balance system, which comprises a detection module, a control module, a load module and vanadium battery modules; the vanadium battery modules are connected in series; the detection module is used for detecting and outputting SOC values of the vanadium battery modules; the control module is connected with the detection module and used for receiving the SOC values and connecting the load module into one of the vanadium battery modules according to the SOC values. The detection module can detect the SOC values of the vanadium battery modules, the control module can insert a load into one of the vanadium battery modules according to the SOC values, the vanadium battery modules inserted into the load module can discharge through the load module, the SOC values of the vanadium battery modules are reduced, and the SOC values of the vanadium battery modules are balanced.

RELATED APPLICATIONS

This application claims priority to and the benefit of Chinese PatentApplication No. 202111287458.6 filed on Nov. 2, 2021, the disclosure ofwhich is expressly incorporated herein by reference in its entirety.

TECHNICAL FIELD

The application relates to the field of vanadium batteries, inparticular to a vanadium battery SOC balance system.

BACKGROUND

The vanadium battery is a storage battery and can store energy byutilizing different chemical potential energies of vanadium ions indifferent oxidation states. The vanadium battery has the advantages ofhigh charging and discharging efficiency, recyclable electrolyte and thelike.

It can be appreciated that a plurality of galvanic piles can beconnected between a positive electrode electrolyte tank and a negativeelectrode electrolyte tank, and all galvanic piles are established tiesand are together can improve battery capacity, and all galvanic pilesare parallelly connected and are together can raise power, consequentlyadopt earlier the mode of establishing ties again parallelly connectedto form the better battery of performance, nevertheless can make thepipeline loss great, and pipeline current increases simultaneouslycauses the galvanic pile to destroy easily. However, when the liquidpath is disconnected, the cell is divided into several groups ofparallel-connected cell stacks, and one positive electrolyte tank andone negative electrolyte tank are provided for each group of cellstacks, and after a long-time operation, the SOC may be unbalanced,thereby affecting the battery capacity.

SUMMARY

In order to improve the problem of SOC unbalance, the applicationprovides a vanadium battery SOC balance system.

The SOC balance system of the vanadium redox battery adopts thefollowing technical scheme:

a vanadium battery SOC balance system comprises a detection module, acontrol module, a load module and a plurality of vanadium batterymodules;

the vanadium battery modules are sequentially connected in series;

the detection module is used for detecting and outputting SOC values ofthe vanadium battery modules;

the control module is connected with the detection module and used forreceiving the SOC values and connecting the load module into one of thevanadium battery modules according to the SOC values.

By adopting the technical scheme, the detection module can detect theSOC values of the vanadium battery modules, the control module caninsert the load into one of the vanadium battery modules according tothe SOC values, so that the vanadium battery module inserted into theload module can discharge through the load module, the SOC value of thevanadium battery module is further reduced, and the SOC values of thevanadium battery modules are balanced.

Optionally, the number of the vanadium redox battery modules is two, andthe two vanadium redox battery modules are respectively a first vanadiumredox battery module and a second vanadium redox battery module;

the first vanadium battery module is connected with the second vanadiumbattery module in series;

the detection module is used for detecting the SOC value of the firstvanadium battery module and outputting an SOC1 value, and is used fordetecting the SOC value of the second vanadium battery module andoutputting an SOC2 value;

the control module is connected with the detection module and used forreceiving the SOC1 value and the SOC2 value and connecting the loadmodule into the first vanadium battery module or the second vanadiumbattery module according to the difference value of the SOC1 value andthe SOC2 value.

Through adopting above-mentioned technical scheme, the detection modulecan detect the SOC value of first vanadium battery module and secondvanadium battery module, and control module can insert the load intofirst vanadium battery module or second vanadium battery moduleaccording to the difference of SOC1 value and SOC2 value for firstvanadium battery module and second vanadium battery module can dischargethrough the load module, and then reach that SOC1 value is close withSOC2 value, so that the SOC value of first vanadium battery module andsecond vanadium battery module is balanced.

Optionally, the load module is respectively connected in parallel to thefirst vanadium battery module and the second vanadium battery module,and loops of the load module connected with the first vanadium batterymodule and the second vanadium battery module are respectively providedwith at least one controllable switch;

the control module is used for outputting a first closing signal whenthe difference value between the SOC1 value and the SOC2 value is largerthan a first preset value, and outputting a second closing signal whenthe difference value between the SOC1 value and the SOC2 value issmaller than a second preset value;

the at least one controllable switch is positioned on a loop of the loadmodule connected with the first vanadium battery module and is used forbeing closed when receiving a first closing signal;

and the at least one controllable switch positioned on the loop of theload module connected with the second vanadium battery module is usedfor closing when receiving a second closing signal.

By adopting the technical scheme, when the difference value between theSOC1 value and the SOC2 value is larger than a first preset value, thefirst vanadium battery module is connected to the load module todischarge. When the difference value between the SOC1 value and the SOC2value is smaller than a second preset value, the second vanadium batterymodule is connected to the load module to discharge, so that thedifference value between the SOC1 value and the SOC2 value is controlledwithin an allowable range, and the SOC is balanced.

Optionally, the first vanadium redox battery module and the secondvanadium redox battery module both include a positive electrolyte tank,a negative electrolyte tank and a plurality of parallel electric stacks;

the anode electrolyte tank is respectively communicated with the anodeand the cathode of each electric pile through pipelines, and the cathodeelectrolyte tank is respectively communicated with the anode and thecathode of each electric pile through pipelines;

the load module is connected in parallel with the electric pile of thefirst vanadium battery module and the electric pile of the secondvanadium battery module.

Optionally, a loop of the load module connected to the first vanadiumredox battery module and a loop of the load module connected to thesecond vanadium redox battery module have a common branch, and the atleast one controllable switch located on the loop of the load moduleconnected to the first vanadium redox battery module and the at leastone controllable switch located on the loop of the load module connectedto the second vanadium redox battery module form a double-poledouble-throw controllable switch.

Optionally, the pipeline connected with the anode electrolyte tank andthe pipeline connected with the cathode electrolyte tank are bothprovided with a circulating pump.

Through adopting above-mentioned technical scheme, the circulating pumpcan be with anodal electrolyte and negative pole electrolyte pumpsending to each pile.

Optionally, the control module includes a processing unit and a controlunit;

the processing unit is connected with the detection module and is usedfor receiving the SOC1 value and the SOC2 value, calculating thedifference value of the SOC1 value and the SOC2 value and outputting thedifference value of the SOC1 value and the SOC2 value;

the control unit is connected with the processing unit and used forreceiving the difference value between the SOC1 value and the SOC2value, outputting the first closing signal when the difference valuebetween the SOC1 value and the SOC2 value is larger than the firstpreset value, and outputting the second closing signal when thedifference value between the SOC1 value and the SOC2 value is smallerthan the second preset value.

Optionally, a balance pipe is further connected between the positiveelectrode electrolyte tank and the negative electrode electrolyte tankin the first vanadium battery module and between the positive electrodeelectrolyte tank and the negative electrode electrolyte tank in thesecond vanadium battery module, and controllable balance valves arerespectively arranged on the balance pipes;

the liquid level detection device is used for detecting the liquid levelin each positive electrolyte tank and each negative electrolyte tank andoutputting liquid level detection signals;

the control unit is also connected with a liquid level detection device,is used for receiving a liquid level detection signal and outputting astarting signal when the difference value of the liquid level valuesreflected by the liquid level detection signal is smaller than adifference preset value; the liquid level detection device is also usedfor outputting an adjusting signal when the difference value of theliquid level values reflected by the liquid level detection signal isgreater than a difference preset value;

the controllable balance valve is connected with the control unit and isused for being opened when the adjusting signal is received;

the detection module is further used for detecting the first vanadiumbattery module and the second vanadium battery module when receiving astarting signal.

By adopting the technical scheme, when the liquid level differencebetween the positive electrolyte and the negative electrolyte is toolarge, the balance valve needs to be opened to balance the liquid levelsof the positive electrolyte and the negative electrolyte, and then theSOC value of the first vanadium battery module and the SOC value of thesecond vanadium battery module are detected.

In summary, the present application includes at least one of thefollowing beneficial technical effects:

1. the detection module can detect the SOC values of the first vanadiumbattery module and the second vanadium battery module, the controlmodule can insert loads into the first vanadium battery module or thesecond vanadium battery module according to the difference value of theSOC1 value and the SOC2 value, the first vanadium battery module and thesecond vanadium battery module can discharge through the load module,the SOC1 value is close to the SOC2 value, and the SOC values of thefirst vanadium battery module and the second vanadium battery module arebalanced.

Additional aspects and advantages will be apparent from the followingdetailed description of preferred embodiments, which proceeds withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system schematic diagram of a vanadium redox battery SOCbalancing system according to an embodiment of the present application.

FIG. 2 is a schematic circuit diagram of a vanadium redox battery SOCbalancing system according to an embodiment of the present application.

FIG. 3 is another circuit schematic diagram of the vanadium redoxbattery SOC balancing system according to the embodiment of the presentapplication.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In order to make the objects, technical solutions and advantages of thepresent application more apparent, the present application is furtherdescribed in detail below with reference to FIG. 1-3 and theembodiments. It should be understood that the specific embodimentsdescribed herein are merely illustrative of the present application andare not intended to limit the present application.

The embodiment of the application discloses a vanadium redox battery SOCbalance system. Referring to FIGS. 1 and 2 , the vanadium battery SOCbalancing system includes a detection module 1, a control module 2, aload module 5, and a plurality of vanadium battery modules. The SOCvalues of the vanadium battery modules are detected through thedetection module 1, so that the control module 2 can control the loadmodule 5 to be connected into one of the vanadium battery modulesaccording to the SOC values to consume the electric energy of thevanadium battery modules, and further the SOC values of the vanadiumbattery modules are balanced.

Specifically, two vanadium battery modules may be provided. When thereare two vanadium battery modules in the vanadium redox battery SOCbalance system of the present application, the two vanadium batterymodules are a first vanadium battery module 3 and a second vanadiumbattery module 4, respectively, for the purpose of differentiation.Further, the detection module 1 detects the SOC values of the firstvanadium battery module 3 and the second vanadium battery module, sothat the control module 2 can control the first vanadium battery module3 or the second vanadium battery module 4 to be connected to the loadmodule 5 to consume electric energy according to the difference betweenthe SOC values of the first vanadium battery module 3 and the secondvanadium battery module 4, and further the SOC values of the firstvanadium battery module 3 and the second vanadium battery module 4 arebalanced.

The first vanadium battery module 3 is connected in series with thesecond vanadium battery module 4. The first vanadium redox batterymodule 3 and the second vanadium redox battery module 4 both comprise apositive electrolyte tank 31 and a negative electrolyte tank 32 and aplurality of parallel electric piles 33, and the two groups of parallelelectric piles 33 are connected in series. Since the first vanadiumbattery module 3 and the second vanadium battery module 4 are connectedin the same manner, the first vanadium battery module 3 is taken as anexample in the embodiment of the present application.

The positive electrolyte tank 31 and the negative electrolyte tank 32 inthe first vanadium redox battery module 3 are respectively communicatedwith the positive electrode and the negative electrode of each electricpile 33 through pipelines 6, and circulating pumps 7 are furtherarranged on the pipelines 6 communicated with the positive electrolytetank 31 and the pipelines 6 communicated with the negative electrolytetank 32, so that positive electrolyte can circulate between the positiveelectrolyte tank 31 and each electric pile 33, and similarly, negativeelectrolyte can circulate between the negative electrolyte tank 32 andeach electric pile 33.

Moreover, a balance pipe is provided between the positive electrodeelectrolyte tank 31 and the negative electrode electrolyte tank 32, andthe balance pipe enables the positive electrode electrolyte tank 31 andthe negative electrode electrolyte tank 32 to be communicated. Ofcourse, the balance pipe is further provided with a controllable balancevalve 8, so that when the liquid level difference between the positiveelectrolyte tank 31 and the negative electrolyte tank 32 is large, thecontrollable balance valve 8 is controlled to open, so that the liquidlevels in the positive electrolyte pipe and the negative electrolytetank 32 are consistent.

The load modules 5 are respectively connected in parallel to the firstvanadium battery module 3 and the second vanadium battery module 4.Specifically, the load module 5 includes load resistors R connected inparallel to the cell stacks 33 of the first vanadium battery module 3and the cell stacks 33 of the second vanadium battery module 4,respectively. At least one controllable switch is respectively arrangedon a loop of the load resistor R connected with the first vanadiumbattery module 3 and the second vanadium battery module 4. The loadresistor R can be switched into the first vanadium battery module 3 orthe second vanadium battery module 4 by controlling the closed state ofthese controllable switches.

It is worth noting that the number of controllable switches provided onthe circuit where the load resistor R is connected to the first vanadiumbattery module 3 and the second vanadium battery module 4 depends on theconnection manner of the load resistor R to the first vanadium batterymodule 3 and the second vanadium battery module 4. Wherein, acontrollable switch or two controllable switches can be respectivelyarranged on the loop of the load resistor R connected with the firstvanadium battery module 3 and the second vanadium battery module 4.

Referring to FIG. 3 , in particular, a load resistor R is connected inseries with a controllable switch K1, and the load resistor R and thecontrollable switch K1 are connected in parallel with the cell stack 33in the first vanadium battery module 3 and the cell stack 33 in thesecond vanadium battery module 4, respectively. Meanwhile, acontrollable switch K2 is further arranged on a branch of the firstvanadium battery module 3 where the stack 33 is connected with thecontrollable switch K1 or a branch of the first vanadium battery moduleconnected with the load resistor R. Similarly, a controllable switch K3is further provided on the branch of the second vanadium battery module4 where the stack 33 is connected to the controllable switch K1 or thebranch connected to the load resistor R. Obviously, the controllableswitch K1 and the controllable switch K2 are closed at the same time,and the controllable switch K3 is opened, so that the load resistor R isconnected to the first vanadium battery module 3; accordingly, thecontrollable switch K1 and the controllable switch K3 are closed at thesame time, and the controllable switch K2 is opened, so that the loadresistor R is connected to the second vanadium battery module 4. Ofcourse, the controllable switch K1, the controllable switch K2 and thecontrollable switch K3 are all turned off at the same time, i.e. theload resistor R is not switched in.

Referring to FIG. 2 , further, in the present application, in additionto the branch where the load resistor R is located, the loops where theload resistor R is connected to the first vanadium battery module 3 andthe second vanadium battery module 4 also have a common branch.Meanwhile, a controllable switch is respectively arranged on the loopsof the load resistor R connected with the first vanadium battery module3 and the second vanadium battery module 4. Preferably, the controllableswitches respectively disposed on the loops connecting the load resistorR with the first vanadium battery module 3 and the second vanadiumbattery module 4 may be regarded as the same controllable switch K4, andthe controllable switch K4 may be a double-pole double-throw switch.Specifically, two fixed ends of the controllable switch K4 are connectedto both ends of the load resistor R, respectively. And a common branchand a loop of the load resistor R connected with the first vanadiumbattery module 3 and the second vanadium battery module 4 are providedwith a connecting end except the common branch. Two movable ends of thecontrollable switch 4 can be connected with the connection ends on thecommon branch, and are connected with any connection end except thecommon branch on a loop where the load resistor R is connected with thefirst vanadium battery module 3 and the second vanadium battery module 4to form a loop, so that the load resistor R is connected into the firstvanadium battery module 3 or the second vanadium battery module 4. Ofcourse, the two active ends of the controllable switch 4 are notconnected to the three terminals, and then the load resistor R is notconnected to the first vanadium battery module 3 and the second vanadiumbattery module 4.

Referring to FIGS. 1 and 2 , generally, before SOC detection isperformed on two sets of the positive electrolyte tank 31 and thenegative electrolyte tank 32, it is first necessary to make the liquidlevels in the two sets of the positive electrolyte tank 31 and thenegative electrolyte tank 32 uniform. Therefore, the vanadium redoxbattery SOC balance system of the application also comprises a liquidlevel detection device 9.

The liquid level detection device 9 is used for detecting the liquidlevel in each positive electrolyte tank 31 and each negative electrolytetank 32 and outputting a liquid level detection signal. Preferably, theliquid level detection device 9 is a liquid level sensor. Of course, ameasuring instrument having a function of measuring a liquid level, suchas a liquid level meter, may also be employed.

The control module 2 is connected with the liquid level detection device9, is used for receiving the liquid level detection signal andoutputting a starting signal when the difference value of the liquidlevel values reflected by the liquid level detection signal is smallerthan the preset difference value; and the liquid level detection circuitis also used for outputting an adjusting signal when the differencevalue of the liquid level values reflected by the liquid level detectionsignal is greater than the preset difference value. Wherein the controlmodule 2 comprises a processing unit 21 and a control unit 22.

The control unit 22 is connected with the liquid level detection device9, and is used for receiving the liquid level detection signal andoutputting a starting signal when the difference value of the liquidlevel values reflected by the liquid level detection signal is smallerthan the preset difference value; and the liquid level detection circuitis also used for outputting an adjusting signal when the differencevalue of the liquid level values reflected by the liquid level detectionsignal is greater than the preset difference value.

It should be noted that before SOC detection is performed on the twosets of the positive electrolyte tank 31 and the negative electrolytetank 32, the liquid level difference between the two sets of thepositive electrolyte tank 31 and the negative electrolyte tank 32 may bezero, may be smaller, and may be larger. In general, it is allowablethat the initial difference between the liquid level values of the twosets of the positive electrolyte tank 31 and the negative electrolytetank 32 is small, i.e. the later operation such as SOC balancing is notgreatly affected. Therefore, when the difference value of the liquidlevel values reflected by the liquid level detection signals is smallerthan the preset difference value, the control unit 22 can output a startsignal. Specifically, the liquid level difference is a differencebetween the liquid levels of the positive electrode electrolyte tank 31and the negative electrode electrolyte tank 32 of the same group. In thepresent application, the difference preset value is 20 cm. Of course,the preset value of the difference value can be adaptively adjustedaccording to actual conditions.

The controllable balancing valve 8 is connected to the control unit 22for receiving the adjustment signal and is opened upon receipt of theadjustment signal. At this time, the positive electrode electrolyte tank31 and the negative electrode electrolyte tank 32 of the same group arecommunicated, and the liquid in one electrolyte tank with a higherliquid level flows to the other electrolyte tank, so that the liquidlevels of the two electrolyte tanks are the same. When the adjustment ofthe liquid in the two electrolyte tanks is completed, the controllablebalance valve 8 is closed. Specifically, the liquid levels of thepositive electrolyte tank 31 and the negative electrolyte tank 32 may bedetected by the liquid level detection device 9, and when the liquidphases of the positive electrolyte tank 31 and the negative electrolytetank 32 are the same, the control unit 22 controls the controllablebalance valve 8 to close. Of course, it is also possible to set theopening time for the controllable balance valve 8, and after the controlunit 22 controls the controllable balance valve 8 to open, and after thecontrollable balance valve 8 is opened for a preset time period, thecontrollable balance valve 8 is automatically closed. The abovedescription provides only two control methods as references, and doesnot limit other control methods. Accordingly, the control unit 22outputs an activation signal after the controllable balancing valve 8has closed.

The detection module 1 is connected to the control unit 22, and isconfigured to receive a start signal, and detect the first vanadiumbattery module 3 and the second vanadium battery module 4 when receivingthe start signal. Specifically, the detection module 1 is used fordetecting the SOC value of the first vanadium battery module 3 andoutputting an SOC1 value; and is used for detecting the SOC value of thesecond vanadium battery module 4 and outputting the SOC2 value. Itshould be noted that the detection module 1 cannot directly detect theSOC1 value of the first vanadium battery module 3 and the SOC2 value ofthe second vanadium battery module 4, so that the detection module 1actually detects the open-circuit voltage, i.e., OCV, between the twopoles of the first vanadium battery module 3 or the second vanadiumbattery module 4, and further converts the open-circuit voltage into acorresponding SOC value.

Further, the processing unit 21 is connected to the detection module 1,and is configured to receive the SOC1 value and the SOC2 value,calculate a difference between the SOC1 value and the SOC2 value, andoutput a difference between the SOC1 value and the SOC2 value.

The control unit 22 is connected to the processing unit 21, and isconfigured to receive a difference between the SOC1 value and the SOC2value, and to output a first closing signal when the difference betweenthe SOC1 value and the SOC2 value is greater than a first preset value,and to output a second closing signal when the difference between theSOC1 value and the SOC2 value is less than a second preset value. Thefirst closing signal is used for controlling at least one controllableswitch on a loop connecting the load resistor R and the first vanadiumbattery module 3 to be closed and other controllable switches to beopened, and the second closing signal is used for controlling at leastone controllable switch on a loop connecting the load resistor R and thesecond vanadium battery module 4 to be closed and other switches to beopened.

It can be understood that the difference between the SOC1 value and theSOC2 value is greater than the first preset value, which indicates thatthe SOC1 value of the first vanadium battery module 3 is greater thanthe SOC2 value of the second vanadium battery module 4, and thedifference between the SOC1 value and the SOC2 value is greater than thefirst preset value. At this time, the control unit 22 needs to controlat least one controllable switch on the loop where the load resistor Ris connected with the first vanadium battery module 3 to be closed, andsimultaneously control other controllable switches to be opened, so thatthe load resistor R is connected to the first vanadium battery module 3to consume the energy of the first vanadium battery module 3 through theload resistor R, thereby reducing the SOC1 value.

Similarly, the difference between the SOC1 value and the SOC2 value issmaller than the second preset value, which can indicate that the SOC1value of the first vanadium battery module 3 is smaller than the SOC2value of the second vanadium battery module 4, and the differencebetween the SOC1 value and the SOC2 value is smaller than the secondpreset value, where it should be noted that the second preset value is anegative number. At this time, the control unit 22 needs to control atleast one controllable switch on the loop connecting the load resistor Rand the second vanadium battery module 4 to be closed, andsimultaneously control other controllable switches to be opened, so thatthe load module 5 is connected to the second vanadium battery module 4to consume the energy of the second vanadium battery module 4 throughthe load resistor R, thereby reducing the SOC2 value, and achieving theeffect of balancing the SOC values of the first vanadium battery module3 and the second vanadium battery module 4.

Besides, when the difference between the SOC1 value and the SOC2 valueis greater than the second preset value and less than the first presetvalue, it indicates that the difference between the SOC1 value of thefirst vanadium battery module 3 and the SOC2 value of the secondvanadium battery module 4 is within the allowable range. At this time,the control unit 22 controls all the controllable switches to be turnedoff so that the load resistor R is not connected into the first vanadiumbattery module 3 and the second vanadium battery module 4.

In the present application, the first preset value is 2%, and the secondpreset value is −2%, and of course, the first preset value and thesecond preset value can be adaptively designed according to actualsituations. The liquid level detection process, the SOC detectionprocess and the SOC balance process are processes of starting andpreprocessing stages of the vanadium battery SOC balance system.

Further, after the SOC balancing system enters a normal operating state,the first preset value is changed to 5%, and the second preset value ischanged to −5%, that is, when the difference between the SOC1 value andthe SOC2 value is greater than 5%, the load resistor R is connected tothe first vanadium battery module 3, when the difference between theSOC1 value and the SOC2 value is less than −5%, the load resistor R isconnected to the second vanadium battery module 4, and when thedifference between the SOC1 value and the SOC2 value is greater than −5%and less than 5%, the connection state of the load resistor R with thefirst vanadium battery module 3 and the second vanadium battery module 4is maintained.

In addition, in the art, the detection module 1 and the control module 2generally employ an EMS controller.

When there are three or more vanadium battery modules in the vanadiumbattery SOC balance system of the present application, the differencefrom the vanadium battery SOC balance system having two vanadium batterymodules is only that: and the vanadium battery modules are sequentiallyconnected in series. Similarly, the parallel electric stacks in eachvanadium battery module are connected together in series in sequence.

At this time, load resistors R are respectively connected in parallel tothe cell stacks of each vanadium battery module. And at least twocontrollable switches are respectively arranged on a loop of the loadresistor R connected with each vanadium battery module. The loadresistor R can be connected to one of the vanadium battery modules bycontrolling the closed state of the controllable switches. Theconnection mode of the load resistor R and the plurality of vanadiumbattery modules can refer to the connection mode of the load resistor Rand the first vanadium battery module 3 and the second vanadium batterymodule 4. It is worth mentioning that the controllable switch in serieswith the load resistor R is a common controllable switch in the loopwhere the load resistor R is connected to each vanadium battery module.

The processing unit 21 is configured to receive all the SOC values,compare all the SOC values to determine a maximum SOC value and aminimum SOC value, and then calculate and output a difference betweenthe maximum SOC value and the minimum SOC value.

The control unit 22 is configured to receive a difference between themaximum SOC value and the minimum SOC value, and output a third closesignal when the difference is greater than a first preset value. Thethird closing signal is used for controlling the two controllableswitches on a loop, connected with the load resistor R, of the vanadiumbattery module corresponding to the maximum SOC value to be closed, andsimultaneously controlling the other controllable switches to be opened,so that the load resistor R is connected to the vanadium battery modulecorresponding to the maximum SOC value, the energy of the vanadiumbattery module is consumed through the load resistor R, and the SOCvalue of the vanadium battery module is reduced.

And when the difference value between the maximum SOC value and theminimum SOC value is smaller than the first preset value, the differencevalue of the SOC values of any two vanadium battery modules is in anallowed range. At this time, the control unit 22 controls all thecontrollable switches to be turned off, so that the load resistor R isnot connected into any vanadium battery module.

Similarly, when the SOC balancing system enters a normal operatingstate, the first preset value is changed to 5%, that is, the differencebetween the maximum SOC value and the minimum SOC value is greater than5%, the load resistor R is connected to the vanadium battery modulecorresponding to the maximum SOC value, and when the difference betweenthe maximum SOC value and the minimum SOC value is less than 5%, theconnection state between the load resistor R and the vanadium batterymodules is maintained.

The implementation principle of the SOC balance system of the vanadiumredox battery in the embodiment of the application is as follows: andsimultaneously connecting the load module 5 with a plurality of vanadiumbattery modules, and arranging a controllable switch on a loop of theload module 5 connected with each vanadium battery module. The SOCvalues of the vanadium battery modules are detected through thedetection module 1, and the control module 2 accesses the load module 5into one of the vanadium battery modules according to the SOC values, sothat the vanadium battery modules can consume energy through the loadmodule 5, and further SOC value balance is achieved.

The foregoing is a preferred embodiment of the present application andis not intended to limit the scope of the application in any way, andany features disclosed in this specification (including the abstract anddrawings) may be replaced by alternative features serving equivalent orsimilar purposes, unless expressly stated otherwise. That is, unlessexpressly stated otherwise, each feature is only an example of a genericseries of equivalent or similar features.

It will be obvious to those having skill in the art that many changesmay be made to the details of the above-described embodiments withoutdeparting from the underlying principles of the invention. The scope ofthe present invention should, therefore, be determined only by thefollowing claims.

What is claimed is:
 1. A vanadium battery SOC balancing system,comprising a detection module, a control module, a load module andmultiple vanadium battery modules; the multiple vanadium battery modulesare series-connected in sequence; the detection module is configured todetect and output SOC values of the multiple vanadium battery modules;the control module is connected to the detection module, and configuredto receive the multiple SOC values, and connect the load module to oneof the multiple vanadium battery modules according to the sizes of themultiple SOC values.
 2. The vanadium battery SOC balancing system asclaimed in claim 1, wherein two of the vanadium battery modules areprovided, being a first vanadium battery module and a second vanadiumbattery module respectively; the first vanadium battery module andsecond vanadium battery module are connected in series; the detectionmodule is configured to detect an SOC value of the first vanadiumbattery module and output an SOC1 value, and configured to detect an SOCvalue of the second vanadium battery module and output an SOC2 value;the control module is connected to the detection module, and configuredto receive the SOC1 value and SOC2 value, and connect the load module tothe first vanadium battery module or second vanadium battery moduleaccording to the difference between the SOC1 value and SOC2 value. 3.The vanadium battery SOC balancing system as claimed in claim 2, whereinthe load module is separately connected in parallel with the firstvanadium battery module and second vanadium battery module, and circuitsconnecting the load module to the first vanadium battery module andsecond vanadium battery module are respectively provided with at leastone controllable switch; the control module is configured to output afirst closure signal when the difference between the SOC1 value and SOC2value is greater than a first preset value, and configured to output asecond closure signal when the difference between the SOC1 value andSOC2 value is less than a second preset value; the at least onecontrollable switch located on the circuit connecting the load module tothe first vanadium battery module is configured to close when the firstclosure signal is received; the at least one controllable switch locatedon the circuit connecting the load module to the second vanadium batterymodule is configured to close when the second closure signal isreceived.
 4. The vanadium battery SOC balancing system as claimed inclaim 3, wherein the first vanadium battery module and second vanadiumbattery module each comprise a positive electrode electrolyte tank, anegative electrode electrolyte tank and multiple parallel-connectedstacks; the positive electrode electrolyte tank is in communication witha positive electrode and a negative electrode of each stack separatelyvia a pipeline, and the negative electrode electrolyte tank is incommunication with the positive electrode and negative electrode of eachstack separately via a pipeline; the load module is connected inparallel with the stacks of the first vanadium battery module and thestacks of the second vanadium battery module.
 5. The vanadium batterySOC balancing system as claimed in claim 4, wherein the circuitconnecting the load module to the first vanadium battery module and thecircuit connecting the load module to the second vanadium battery modulehave a common branch, and the at least one controllable switch locatedon the circuit connecting the load module to the first vanadium batterymodule and the at least one controllable switch located on the circuitconnecting the load module to the second vanadium battery module form adouble-pole double-throw controllable switch.
 6. The vanadium batterySOC balancing system as claimed in claim 5, wherein the pipelineconnected to the positive electrode electrolyte tank and the pipelineconnected to the negative electrode electrolyte tank are each providedwith a circulating pump.
 7. The vanadium battery SOC balancing system asclaimed in claim 6, wherein the control module comprises a processingunit and a control unit; the processing unit is connected to thedetection module, configured to receive the SOC1 value and SOC2 value,configured to compute the difference between the SOC1 value and SOC2value, and configured to output the difference between the SOC1 valueand SOC2 value; the control unit is connected to the processing unit(21), configured to receive the difference between the SOC1 value andSOC2 value, and configured to output the first closure signal when thedifference between the SOC1 value and SOC2 value is greater than thefirst preset value, and configured to output the second closure signalwhen the difference between the SOC1 value and SOC2 value is less thanthe second preset value.
 8. The vanadium battery SOC balancing system asclaimed in claim 7, wherein balancing pipes are further connectedbetween the positive electrode electrolyte tank and negative electrodeelectrolyte tank in the first vanadium battery module and between thepositive electrode electrolyte tank and negative electrode electrolytetank in the second vanadium battery module, and a controllable balancingvalve is provided on each of the balancing pipes; the system furthercomprises a liquid level detection device, the liquid level detectiondevice being configured to detect a liquid level in each positiveelectrode electrolyte tank and each negative electrode electrolyte tank,and output liquid level detection signals; the control unit is furtherconnected to the liquid level detection device, configured to receivethe liquid level detection signals, and configured to output anactivation signal when the difference between liquid level valuesreflected by the liquid level detection signals is less than adifference preset value; and configured to output a regulation signalwhen the difference between liquid level values reflected by the liquidlevel detection signals is greater than a difference preset value; thecontrollable balancing valve is connected to the control unit, andconfigured to open when the regulation signal is received; the detectionmodule is further configured to subject the first vanadium batterymodule and second vanadium battery module to detection when theactivation signal is received.